Magnetic ore-separator



(No Model.) 1'

o. M. BALL. MAGNETIC ORB SEPARATOR.

Patented Dec. 15, 1891.

In p 6.7220) s scams Perms co, mum-um Uivrrsn States ATENT OFrrcE,

CLINTON M. BALL, OF TROY, NEW YORK.

MAGNETIC OR E SEPARATOR.

SPECIFICATION forming part of Letters Patent No.- 465,349, dated December 1-5, 1891.

Pip li tienfil dDecemherl1, 1890. SerialNo.874,384. (NomodeL).

This invention relatestd a novel method of and apparatus LOX separating iron or its crushed ore frOmJt-he impurities with'which such are generallyfound associated and for gra i g ty separatedproducts.

In a gerior patent granted to me and Shel- QlkfiOIton was described a mode of separa- "tion involving as its characteristic feature the passage 'of the mixed iron ore and. gangue through a magnetic field, during which tangential inertia isimparted to the ore by means of a rotary screen interposed between the magnets creating the field and the passage for the ore. In another case was describeda similar mode involving as an additional feature the idea of using two or more magnetic fields and corresponding rotating screens, which were driven at different rates of speed, resulting in the separation of the material operated upon into three grades: concentrate, middlings, and tailings.

The present invention constitutes an improvement more especially upon the apparatus described in the last-mentioned case, although it is also applicable to the case in which a single rotary screen is used. It also involves a new mode of treatment of the magnetic ore. The screens are belted or otherwise geared to a suitable source of motion, so that they may impart the necessary tangential inertia to the material being operated upon to separate said material into proper grades, varying according to the percentage of iron contained therein, and the magnetic fields are varied in strength, so as to adapt the operation of the machine to the character of the ore as to its magnetic susceptibility and preserve the uniformity of the separated products. lVhere the two rotating screens are driven at different speeds, the ability to vary the strength of the field is a matter of difference in speed, which may be somewhat too great or somewhat too slight, to be compoint to secure the best results.

My present invention thereforpiaomprises impurities by passin 1* flfi ugh one or more magnetic field Aa do under the influence of best results. v

It also comprises a series of magnetic fields and means for varying the strength of field magnetism and means for conducting the ore through said fields while under the influence of tangential inertia.

It also consists of a method of separation eral grades, according to the percentage of iron contained, and then recrushing the impure material to mechanically.dissociate the iron, and then withdrawing the said iron from the crushed material.

In the accompanying drawings, whichillusrying out my invention. Fig. 2 is a diagrammatic view illustrating a method of producing variablevelocities in the several rotating screens; and Fig. 3 shows a modification of the electrical system and means for controlling the strength of the field magnetism.

The apparatus is constructed in the form of of each of the drums and upon its shaft is suspended a cylindrical segment of iron 6,

pensated or graduated to exactly the proper an apparatus for separating tfi' r from its g iizlflfm'tia and adjusting the strength JJi tfiefield to the proper point to yield the a chest having the sides 1, ends 2, top 3, and the bottom constructed in the form of several havin the sleeve 7 which forms the .oint of t a 2 considerable importance, as it enables the consisting in first separating the ore into sevtrate the invention, Figure 1 is a longitudinal vertical section of a separating device for carapron 11, i lined toward the surface of the drum D, and I prefbiwgrspend this apron .on a suitable pivotal 1901 Ba p v e It tial to the carrying out of the invention.

per 10 between the drum D and-the adja- -too large to pass through the opening which I desire to maintain between the apron and without injury to the drum and at once reed and operated on the same principles as able air-inlet 15, and the out1et'16 for the cons uspension for the segment on the shaft. Radiating from the lower surface of the segments 6 are a number of magnets 8, which extend almost into contact with the inner surface of the drums. These radiating magnets are wound with insulated wire, and by preference are connected into the eXciting-circuitin such Way as to make the successive poles alternately N and S. The structure 6 7 Sis secured so that the drum may be rapidly rotated around the same and out of contact therewith without disturbing the normal position of the magnetic structure.

While I have given preference to the alternating character of the poles of the magnetic system, I wish to state that this is not essen- In the top of the structure I arrangeahopthe ore a nd gangue. Belowthis I place an with the springr12, whose tendency 1 34 Press the apron toward the drum, actual cm being prevented by the stop 1-3. The purpose of such spring-suspension is that when a lump of ore or other matter happens to be the surface of the drum the apron yields sufficiently to permit the lump to pass through sum'es its normal position. The direction of rotation of the drum D is, as indicated by the arrow, in a direction away from the apronll on the under side of the drum. The hopper h'rises up to a point near the-drum D on the side opposite that occupied by the apron 11 to a point not quite reaching the farthest of the series of magnets inside the drum.

The drum D is arranged in the same position With reference to hopper 71 that the drum D occupies with reference to hopper h. A combined deflector and apron 1 1 is arranged in a position under drum D similar to that occupied by apron 11 with reference to drum D, for the purpose of insuring the retention of the material delivered from drum D within the influence of the magnet in drum D Hopper 7&2 has its breast rising to a point slightly beyond the last magnet in the drum D I prefer to place the apron 14 slightly closer to drum D than apron 11 is to drum D, and the space between the upper end of the breast of hopper h and the drum D is wider than the similar space bet ween hopper h and drum D. These drums are both driven in the same direction, and both the hoppers h and h are provided with the automatic weighted valves 15 and 25 which are constructset forth in said Letters Patent No. 430,058.

The chest structure is provided with a suitcentrat'ed ore also serves as an inlet for air,

allintermediate points of the structure being practically closed to further this object.

The gearing may consist of a variety of devices, a simple form of which is illustrated in the diagram Fig. 2,in which 18 is the drivingpulley; 19,a belt; 20 and 21, reverse cone-pulleys on the respective shafts 4 and 5, which are connected together bya belt 24. By means of the cone-pulleys the relative speeds of the drum may be varied by steps, after which the field magnetism may be finely graduated to attain the best result.

The apparatus as thus far described is the same asthat illustrated and described in Pat ent No. 449,7 26, issued to me and Sheldon Norton-0skthe 7th day of April, 1891.

Th rafmnefnthis apparatus will be as follows: Assuming, "arexample, that the drum D is given a speed of tw hundred revolutions per minute, the drum D m'gl t to advantage be given aspeed of three hundred per minute. Under these circumstances it is bvious that if the magnetic field be of substahbrl y the same strength in the two drums the tangeytial inertia which will be impressed upon th mass of material clinging to the drums by the magnetic attraction will be considerably greater on drum D compared with that of drum D. The ore and gangue to be separated is passed into the hopper 10 and dropped from that onto apron 11. The ore and gangue, passing down the apron 11, are brought into close proximity to the surface of the drum, and when the first magnetic pole is reached a powerful magnetic attraction is set up for the particles of ore, causing the same to cling to the surface of the drum. As the mass moves forward with the drum, as soon as the lower edge of apron 11 has been passed the tangential inertia, together with the force of gravity, come into play and the unattracted particles of gangue are violently thrown off the drum down into the hopper h, while the remaining particles are held against the drum as it moves to the left. This operation continues upon the mass of ore and gangue as rapidly as it falls from the hopper 10, and when the hopperh has a sufficient quantity in it to cause the Weighted valve to operate the'latter will yield, permitting the gangue to pass away through valve t in proportion as it is received in the hopper it. As the drum- D moves onwardly, the adhering magnetic ore, finally passing the last magnet of the series inside the drum D, reaches a position Where the tangential inertia which has been impressed upon it overcomes the attractive force of the magnet, and the entire mass is IIO IISI

and located relatively as to accomplish thispnrpose. Some of the ore thus projected againstthe drum D isimmediately held there by the magnetic attraction, and such ore as not directly held by the internal magnetic field falls upon the apron 14 and is by itguided into closer proximity to the drum, so that the material will be well spread out and every particle brought within the active range of the magnetic system inside drum D*. As the drum D revolves, the layer of ore passes away from the lower edge of apron 14. The portions which are not rich enough in iron to cling to the external surface of the drum in spite of the increased tangential inertia which has now been impressed upon them fall into the hopper If, and this hopper maybe considered as delivering at the valve 25 a good grade of separated ore, but not the best. The latter on account of its high relative percentage of iron still clings to the surface of drum D so long as it is within the inductive influence of the magnets inside, and upon passing out of their in fiuence to a degree sufficient to overcome the attraction the tangential inertia becomes active and the entire mass, which is then held against the surface of the drum, is projected over the wall of hopper 7 I into hopper 71 where it falls and emerges at the opening 16 at the bottom. During this operation the exhaust-fan produces a powerful current of air at the opening between hopper 72, and the drum D also a powerful current of air between the upper front edge of hopper h and the drum D, as indicated by the curved arrows, and at the same time a substantially horizontal current is established across the hoppers, as indicated by the straight arrows. The eltect of these currents of air is to thoroughly cleanse the material operated upon of all the fine nonunagnetic dust, which can be carried away along with the air discharged by the fan to any desired point. The result is that the immediate vicinity of the apparatus is clean and free from dust. It will thus be seen that the material operated upon is separated into three distinct grades in its passage through the machine: tailings, middlings, and concentrate. The first of these products is free from magnetic material and is disposed of as refuse or as a by-product. The last is pure iron ore. In the middle grade, however, there still remains a percentage of iron in the form of small grains or crystals attached to fragments of gangue. My invention contemplates the separation and recovery of the iron from these impurities, and I attain these results by recrushing or grinding the middlings and passing the recrushed material again through the machine, thus sepawhich it before adhered.

I am well aware that separators have heretofore been proposed in which itwas contemplated to separate the ore into several distinct grades, varying in percentage of iron contained; but, so far as I know, an intermediate grade after such separation has never been acted upon so as to mechanically dissociate the iron and gangue and then acted upon to separate it into its magnetic and non-magthe machine. Now, inasmuch as all ores are and characterof distribution of the magnetic ceptibility, and as even the same material varies moreor less, the speed of the rotating screen or screens which would yield the best results at one time would not at another. If the speed'be too high, the matter thrown off from the first one, instead of being simply gangu e, wi ll contain more orless material which should be classed as middlings and in which occur small particles of ore adhering to the granules of worthless material which are worth recovery. By setting the speed of the screens at precisely the proper limit this difficulty could be obviated; but I prefer to preserve the selective power of the successive parts of the apparatus by varying the strength of the magnetic fields in proper relation to the differin g speeds of the rotating screens, and this may be done byincluding int-he eXciting-circuits of the magnets a variable resistance or which the strength of the field may be increased or decreased until the centripetal and centrifugal forces developed by the magnets and the screens, respectively, reach the exact stage best suited to the ore being worked, which can readily be ascertained byexamination of the products of separation. This be conveniently adjusted while the machine is in operation and is shown diagrammatically at 25 25 in Fig. 1 of the drawings, and at 26 in Fig. 3. Generally the arrangement illustrated in Fig. 3,in which the field magnetism is varied by a single switch, will be sufficient, inasmuch as by such a variation the character of the products of separation of any given ore being operated upon may be preserved uniform by simply manipulating the switch. In the arrangement illustrated in Fig. 1,with independent switches for the magnets corre sponding to the several drums, the selective power of either drum may be varied at will irrespective of the other, thus giving the ap paratus the same capability in effect as-if the relative speed of the two drurgs were changed. Ordinarily, however, a fixed ratio of speed will exist for a particular quality of ore and rating the free iron or ore from the gangue to a net ic components by a second passage through not of the same character as to the amount material-and gangue and their magnetic susvariable resistances, by the adjustment of IIO' resistance is located at any point where it may i the selective power of the apparatus will be 7 ment of a single switch.

made uniform in spite of a slightly-Varying percentage of iron in the ore by the adjust- I do not of course limit myself to the use of avariable resistance for varying the strength of the field magnetism, as many other Ways which Will occur to the electrician might successfully be adopted.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

1. An oreseparator comprising a rotary screen in a magnetic field, means for passing the ore to the screen, and means for varying the strength of the field.

2. An ore-separator comprising a series of rotary screens in successive magnetic fields, meansfor imparting different speeds to the successive screens, means for feeding the ore to the screens in succession, and means for 

